The present invention relates to a radially expandable seal arrangement and, more specifically, to an arrangement for radially expanding a tubular gasket into compressive sealing engagement with the wall of an opening.
The arrangement described below is an improvement upon the invention described in my previously issued U.S. Pat. No. 4,478,437. To the extent necessary for a full and complete understanding of the present invention, the disclosure of U.S. Pat. No. 4,478,437 is incorporated herein by this reference thereto.
In U.S. Pat. No. 4,478,437, an arrangement for sealing a tubular gasket against the wall of an opening in a manhole riser is described. That arrangement includes a radially expandable split sleeve (28) coaxially received within the gasket adjacent the portion of the gasket which is to be expanded. The sleeve, which is shown in additional detail in FIGS. 3-11 of that patent, is expanded (along with the gasket) by use of a scissors-shaped tool (70) which is operated by a hydraulic cylinder (78) operatively connected between the scissor arms of the tool. Two pins are provided on the distal ends of the arms. These pins are inserted into two openings in opposing ends of the split sleeve, and hydraulic pressure is used to expand the sleeve and gasket until the sleeve ends lock in the expanded position.
The arrangement described in U.S. Pat. No. 4,478,437 works well for its intended purpose. However, a relatively strong force must be exerted by the hydraulic tool in order to expand the compression sleeve and gasket into the final locked position. An object of the present invention is to provide an improved arrangement wherein the magnitude of the force required to expand the sleeve into its final locked position is reduced. This allows a corresponding reduction in the size and weight of the tooling used for installation of the gasket, and for greater equalization of the compression forces applied to the gasket.
Another object of the present invention is to provide an alternative arrangement for locking a split sleeve in the expanded position. This alternative arrangement provides a range of locking positions which enable a single sleeve to be used for openings having a relatively wide range of diameters. The resulting "standardization" in sleeve length and structure allows for substantial reductions in sleeve production costs.
These and other objects of the invention are achieved in an arrangement for radially expanding a tubular gasket which comprises a sliding sleeve, a compression sleeve, means for expanding the sliding sleeve, compression sleeve and tubular gasket from a relaxed position into an expanded position, and means for locking the compression sleeve in the expanded position. The sliding sleeve is formed of a thin membrane of relatively rigid material, such as nylon, hypalon or polyester. The sleeve is positioned adjacent an inner surface of that portion of the tubular gasket to be expanded. The compression sleeve formed of a relatively stiff, but resiliently flexible material is disposed immediately adjacent the sliding sleeve such that the sliding sleeve serves as a slip plate for the compression sleeve when the sleeves are expanded against the inner surface of the tubular gasket. In one embodiment, the sliding sleeve is formed in a U-channel shape, and is dimensioned so as to accept the compression sleeve within the upstanding sidewalls of the U-shaped cross-section. The thickness of the upstanding sidewalls is substantially greater than the wall thickness of the remaining portion of the sliding sleeve. The thin portion of the sliding sleeve is designed to stretch or break when the compression sleeve, sliding sleeve and gasket are expanded. If necessary, the sliding sleeve may be segmented into portions (such as by perforations) which break apart when the sliding sleeve is expanded.
The sliding sleeve may be adapted to fit within a groove formed in the inner surface of the tubular gasket, alternatively, the sliding sleeve may be attached to or molded into the inner surface of the tubular gasket. The sliding sleeve may be attached to the outer surface of the compression sleeve.
The sliding sleeve of the present invention may be used with a compression sleeve such as that shown in U.S. Pat. No. 4,478,437. Alternatively, a compression sleeve which locks in a plurality of expanded positions may be used. One embodiment of such a compression sleeve includes a plurality of inwardly projecting teeth on a first end of the sleeve, and at least one tooth engaging surface on a second opposing end of the sleeve which may engage any one of the plurality of inwardly projecting teeth to lock the sleeve in a corresponding plurality of expanded positions. The second end of the sleeve is formed to include a recess to receive one or more of the plurality of teeth so as to maintain a relatively smooth and continuous profile around the outer circumference of the sleeve.
In another embodiment, the compression sleeve comprises a C-shaped structure and a separate, arc-shaped locking mechanism which engages the ends of the C-shaped sleeve so as to lock the sleeve in an expanded position, and so as to form a relatively smooth and continuous profile around the outer circumference of the compression sleeve/locking mechanism assembly. In this arrangement, teeth-like structures may be provided on opposing ends of the C-shaped sleeve. Mating teeth-like structures are similarly provided on the arc-shaped element to engage the teeth-like structures on the opposing ends of the sleeve to secure the sleeve into an expanded and locked position. The arc-shaped element may be molded into the gasket (or otherwise pre-attached to the inner surface of the gasket) for ease of use and installation.
In either embodiment of the sleeve, a pair of tabs may be provided to engage an appropriate tool for expanding the sleeve and gasket into position. The tabs may be designed to fail when a predetermined amount of force is applied thereto in order to limit the magnitude of the force which may be applied to the sleeve/gasket assembly.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.